Technical Abstract:
Sample sets of ground corn and the corresponding distillers dried grains with solubles (DDGS) were collected from three commercial plants in Iowa. Phenolic acids were analyzed by high performance liquid chromatography coupled with diode array and/or mass spectrometry. The antioxidant activity was analyzed by ferric reducing antioxidant power (FRAP) assay. The five phenolic acids identified in DDGS were vanillic, caffeic, p-coumaric, ferulic, and sinapic acids, with ferulic and p-coumaric acids accounting for about 80% of the total phenolic acids. In relative term, the phenolic acids profile of DDGS was comparable to that of corn. However, in term of concentration per gram basis, total phenolic acids in DDGS was 3.4 fold higher than that of corn, while FRAP capacity of DDGS was 2.6 fold increase over corn. These observations suggest that there was little change in individual phenolic acids during dry grind processing. Furthermore, significant variation was observed in measured in total phenolic acids and antioxidant capacity among plants.